The physicomechanical aspects of the emergence of the planets are discussed, based on the concept of accretion from solid bodies and particles which, together with the gases, made up the protoplanetary cloud enveloping the sun in the early phases of its development. The idea of accretion was extensively developed in Shmidt's theory and later in the physicochemical studies of meteorites carried out by Urey and others. The evolution of the gas-dust protoplanetary cloud and the formation of a cluster of solid bodies is studied first. Then the fundamental laws of dynamics in a rotating system of gravitating bodies with inelastic collisions and the process of accumulation of planets by the aggregation of solid bodies and particles are investigated. Finally, a method is developed for evaluating the primary temperature of the earth, and the question of primary inhomogeneities in the earth mantle is discussed.